Automatic cut-off mechanism for electric can opener



R. S. KNAPP April 28, 1964 AUTOMATIC CUT-OFF' MECHNISM FOR ELECTRIC CAN OPENER Filed ril 20 1962 United States Patent O 3,130,492 AUTMA'I'IC CUT-GFF MECISM FR ELECTREQ CAN GPENER Robert S. Knapp, St. Louis, M0., assigner to Knapp- Monarch Company, St. Louis, Mo., a corporation of Delaware Fied Apr. 20, 1962, Ser. No. 190,195 6 Claims. (Cl. 30-4) This invention relates to a can opener which is operated by means of an electric motor, .automatic means being provided to stop 'the operation of the motor after the lid of .the can has been completely severed.

`One object or the invention is to provide a can opener of the general type referred to which is comparatively simple and inexpensive to manufacture.

Another object thereof is Ito provide a can rotating wheel which may be rotated at relatively low speed by a fractional horse power motor through simple step-down gearing.

Another object is -to provide a lid cutter so mounted in relation to .the can rotating wheel that it may be spaced therefrom for insertion of the can and moved by a hand lever into cutting position with respect to the can lid and the can rotating wheel.

A further object is to provide the lever that mounts the cutting wheel with a hub that is rotatable in a Wall of the housing for the can opener, the can lid cutting wheel being carried thereby eccentrically relative to .the rotation of the hub and in such a posi-'tion as to tend to keep the hand lever in the lid cutting position as long as a can is being rotated by the can cutting wheel and the lid is not completely severed from ythe can.

Still a further object is to provide -a control switch for the motor which Iis associated with the lever in such manner that it is closed when the lever is moved Vto lid cutting position, and is thereafter retained closed by the drag of the can lid against the cutter wheel until such time as the lid is completely severed from the can and thereupon ceases to eect such drag whereupon spring means effects opening of the switch for automatically stopping the operation of the can opener.

An additional object is to provide the hand lever and its hub with a portion so shaped that a stud secured thereto for mounting the can lid cutting Wheel presents the wheel at such angle relative to the can rotating wheel that there is etfective drag of the uncut portion of the lid of the can against the can lid cutting wheel suflicient to accomplish the desired result of keeping a normally open switch closed as long as any part of the lid is still uncut from 4the can.

With these and other objects in view, my invention consists in the construction, and :arrangement and combination of the various pants of my can opener, whereby the objects above contemplated are attained, as hereinafter more fully set forth, pointed out in my claims and illustrated in detail on the accompanying drawing, wherein:

FIG. 1 is a plan view of yan automatic electric can opener embodying my invention, a portion of the housing being cut away and other portions thereof shown in section in order to show internal details.

FIG. 2 is a fragmentary front elevation of the left end of FIG. l.

FIGS. 3 and 4 are `fragmentary horizontal and vertical sectional views respectively on the lines 3 3 and 4 4 of FIG. 2 showing details of construction, and

FIGS. 5 and 6 are views similar to FIG. 2 showing different positions of the parts during different operations of the can opener.

On the accompanying drawing I have used the reference numeral to indicate a base in the form of a ver- EEAQZ Patented pr. 28, 1964 tical wall, and 12 a cup-shaped cover secured to the base by screws 14. The base 10 and the cover 12 form a housing for the openating mechanism of my can opener.

rl'ihe base lil has an annular hub 15 formed integral therewith as shown in FIGS. 1 and 4 to rotatably support a shaft 15 on which is mounted a can rotating feed wheel 20. The wheel 2@ is of the usual toothed type as shown in FIG. 2 for engaging under the bead 21 of .a can 23 and rotating the can for cutting the lid 25 therefrom as will hereinafter appear.

For rotating the shaft 1.8, a step-down gearing is provided including gear 22 which meshes with a pinion 24 as shown in FIG. l. A gear 26 is integral with the pinion 24 and is driven by a pinion 28 which in turn is integral with a gear 30. The gear 30 meshes with a motor shaft pinion 32 on the shaft of a motor M. The motor M includes the usual field laminations 34, armature 36 and eld coil 38.

Adjacent lthe motor M a switch mounting 4t) is provided on which i-s mounted an upper switch blade 42 and a lower switch blade 44 which have contacts 45 and 4S normally separated from each other by fthe resiliency of the upper switch blade i2 as shown in FIG. 6. The switch contacts are mounted in series in the circuit of the motor M so as to control the energization of such circuit, and the blade 42 is provided with fan insulating button SG.

Referring to FIGS. 2, 3 and 4, the base 10 has an enlarged opening 52 that serves as a bearing in which a hub 56 of a lever Se rotates. The axis of opening 52 is above and to one side of the axis of feed wheel Ztl. A retainer plate 59, apertured `at 59a and 59h for receiving screws to mount the plate against Ithreaded bosses formed on base 10, retains the lever against the inner face of base It) :and retains hub 56 in the opening 52. The lever is .adapted to move from a dot-and-dash line position shown in FIG. 2 to a full line position wherein flange 54a contacts an insulating button Sil on the switch blade 42 for closing the switch `contact 46 against the contact 4S as shown. The lever 54 also has a hump 53 provided with a threaded perforation o@ eccentric to the axis of rotation of the hub S6 for the reception of a cutter supporting stud 62, the shape of `the humpbeing such as to receive the stud 62 (FIG. 4) at a desired angle in relation to :the axis of the can rotating shaft 1S. A can lid cutter 64 is rotatable on the stud 62 and a coil spring 66 fis interposed between the cutter and the hump 53. The cutter 54 has a sharpcned peripheral edge for cutting through the can lid 25 as shown in FIG. 2 and lfor continuing the cutting of the lid as the wheel 29 is rotated as shown in FIG. 5.

A sheet met can top guide is provided with a canengaging part 68a and a mounting part 68h having a detent 68C entering an aperture in hump 53 to be secured to and movable with the hump 5S. A stationary sheet metal can top guide 70 is provided substantially in alignment with part @tia during the cutting operation as in FIG. 5. The guides 68 and li determine the elevation of the top of the can, and a guide 72 for engaging the can side extends outwardly from base l@ to assist in properly positioning a can with respect to the can rotating wheel 2t? and the can lid cutter 64 during operation.

A sheet metal magnet supporting arm '74 is provided on which is mounted a magnet 76, the manner of mounting being a headed stud 78 loosely received through a perforation of the arm 74. A single screw 79 mounts the guide 7i) and arm 74.

The automatic can opener herein disclosed may be mounted on any appropriate stand, or preferably the back wall of cup-shaped cover i2 (the one opposite the base itl) may be provided with a plurality of keyhole slots for wall mounting of the device in a manner Well known in the art. In actual construction, the base 1i) is a cast part with guide 72 integral therewith, and with all operative parts mounted on the base. rthe cover l2 is merely a hollow part that neatly encloses all the operative parts.

Practical Operation In the operation of my automatic can opener, the lever 54 is raised to the dot-and-dash line position of FIG. 2 which swings the can lid cutter 64 also to the dot-anddash line position permitting entry of the bead 21 of the can 23 between the wheel 2i? and the cutter 64; so as to properly rest on the top of the Wheel 2t? for traction in the usual manner. The lever 54 is now swung downwardly to the full line position which first causes the cutter 64 to overlie the bead 2l of the can and then to move to position to overlap the wheel 2i? as shown in FIG. 4 and to thereby cut into the lid 25 as shown. During the last few degrees of this downward movement the lever 54 engages the button 5t? and closes the contact 46 against the contact 4S.

Accordingly, the motor M is energized for rotating the can as shown in EEG. 5, the wheel rotating counterclockwise and the far side of the can moving in the direction of the arrow a while the near side thereof moves in the direction of the arrow b. The portion 25a of the lid 25 has already been cut, and that portion of the lid that has not been cut and is moving in the direction of the arrow a is causing a drag against the cutter 64 tending to push it to the left and thereby rotate the hub 56 of the lever 54 clockwise. This results in the lever 54 keeping the contact 46 in engagement with the contact 43 as illustrated even though the operators hand has been removed from the lever 54. Accordingly, as soon as the motor M starts to operate, the lever 54 can be released and the can lid cutting operation will continue because of the drag keeping the lever 54 depressed and thereby the circuit for the motor energized.

When the can lid has been cut all the way through as shown in FIG. 6 there is no longer a drag on the cutter that keeps the contacts closed. Accordingly the spring bias of the upper switch blade 42 will separate the contacts as in FIG. 6, raising the lever to a slight angle relative to the upper edge of the base l@ as illustrated. Thus the motor M is de-energized automatically upon completion of the lid cutting operation.

The mechanism for accomplishing this automatic operation is comparatively simple, consisting in the axis of the can lid cutter 64 being eccentric relative to the axis of the opening 52 in which the hub 56 rotates. These two axes are shown at Sil and 52 respectively in FIG. 2 whereas the axis of the cutter when the lever 54. is in the raised (dot-and-dash line) position is indicated at 84. In FIG. the axis of the cutter is also at 8l) whereas in FIG. 6 it has moved from 8l) to an axis indicated 86 where the contacts 46 and 4% have been separated. In FIG. 5, during a cutting operation, the axis Sti of the cutter is located between the vertical planes through the axis of shaft 18 and the axis 82 about which the lever 54 pivots. This is the position of rest of lever 54 until such time as it is lifted for another can lid cutting operation.

From the foregoing it will be seen that the automatic can opener herein disclosed and described is inherently simple and involves only a limited number of elements necessary to effect the desired operation, thereby providing a device which is less expensive than the complex openers that heretofore have been devised and have been too costly to be commercially successful. The wellknown hand-crank-operated openers are easy and quick in their operation and are relatively inexpensive and, in order to provide a marketable power-operated can opener, it is essential that it have a relatively low selling price, so that it may compete with the perfected hand-operated can openers presently available. Thus, the automatic can opener construction of this invention is simple, compact, and provides the necessary functional elements, while reducing the total number -of elements necessary to achieve proper operation.

Some changes may be made in the construction and arrangement of the parts of my automatic can opener without departing from the real spirit and purpose of my invention. It is my intention therefore to cover by my claims such modified forms of structure or use of mechanical equivalents as may reasonably be included within their scope.

I claim:

`l. Automatic cut-olf mechanism for an electric can opener comprising a base, a can rotating shaft journaled therein, a can rotating wheel on said shaft, a motor, stepdown gearing between said motor and said can rotating shaft, said base having an opening spaced from said can rotating shaft, a lever having a hub rotatable in said opening, a retainer plate for said lever effective to retain said hub in said opening, a can lid cutter carried by said lever at a position oifset from the axis of rotation of said hub, a control switch for said motor, said control switch being normally resiliently urged into open position, said lever in can opening position operating to cause said control switch to close, said cutter in the lid cutting position being urged in a direction to rotate said hub and lever into switch closing position, and thereby keep said control switch closed as long as any part of the lid is uncut relative to the can but allowing it to open when the lid is completely severed to effect automatic cut-off.

2. An electric can opener comprising a base, a can rotating shaft journaled therein, a can rotating Wheel carried by said shaft, a motor mounted on said base for driving said can rotating shaft, said base having an opening adjacent said can rotating shaft, a lever having a hub rotatable in said opening, a cut-off switch for said motor biased to open position and operable by said lever to move to motor energizing position, a can lid cutter carried by said lever at a point eccentric to the axis of rotation of said hub so that once the can is manually pierced by the lever the force of the uncut lid rotating against said cutter applies a biasing torque to the lever to maintain the lever in switch-closed position to keep the switch energized Without manually holding it down until the lid is completely severed.

3. A power operated can opener comprising, in combination: frame means, rst journal means rigidly positioned on said frame means and rotatably supporting a drive shaft for a can-rotating feed wheel, and a feed wheel on said drive shaft; an electric motor for driving said drive shaft, and a switch for controlling said motor; said frame means defining a second journal means therein offset from said rst journal means, a hub pivotably mounted in said second journal means, a lever rigidly connected to said hub and extending from said hub and movable therewith, a can lid cutter carried by said hub with the axis of said cutter iixedly located at a position offset from the axis of said second journal means and adapted to be swung by said lever between a non-cutting position, wherein the lid cutter is spaced from said feed wheel, and a lid-cutting position, wherein the lid cutter overlaps a portion of the feed wheel; said lever and said switch being positioned and arranged to have said lever operate to cause said switch to close to initially energize the motor when the lever moves said lid cutter to a position adjacent said lid-cutting position and to maintain said switch closed during the can cutting operation, and said lid cutter when in said lid-cutting position being urged by resistance of a can lid being cut in a direction to rotate said hub and lever and thereby maintain said switch closed so long as any portion of the lid is uncut relative to the can.

4. A can opener as set forth in claim 3 including a first can-engaging means carried on said frame means for engaging the upper edge of a can, a second can-engaging means carried on and movable with said hub for engaging the upper edge of a can when the lid cutter is in lid-cutting position, and said irst and second can-engaging means, When a can lid is being cut, being spaced in substantially the same plane on opposite sides of the overlapping portions of the lid cutter and can rotating wheel.

5. A can opener as set forth in claim 3 including a rst can-engaging means carried on said frame means for engaging the upper edge of a can, a second can-engaging means carried on and movable with said hub for engaging the upper edge of a can when the lid cutter is in lid-cutting position, said rst and second can-engaging means, when a can lid is being cut, being spaced in substantially the same plane on opposite sides of the overlapping portions of the lid cutter and can rotating wheel, and a third can-engaging means iixedly carried on said frame below said can rotating wheel for engaging the side of a can being cut open.

6. A power operated can opener comprising, in combination: ame means, rst journal means rigidly positioned on said frame means and rotatably supporting a drive shaft for a can-rotating feed wheel, and a feed wheel on said drive shaft; an electric motor, step-down gearing between said motor and said drive shaft, and a switch for controlling said motor; said frame means dening a second journal means therein olset from said first journal means, a hub pivotably mounted in said second journal means, an elongated lever rigidly connected to said hub and extending distally from said hub and movable therewith, a can lid cutter carried by said hub with the axis of said cutter iixedly located at a position offset from the axis of said second journal means and adapted to be swung by said lever between a non-cutting position, wherein the lid cutter is spaced from said feed wheel, and a lid-cutting position, wherein the lid cutter overlaps a portion of the feed wheel; said lever and said switch being positioned and arranged to have a portion of said lever distally from said hub move against and cause said switch to close to initially energize the motor when the lever moves said lid cutter to a position adjacent said lid-cutting position and to maintain said switch closed during the can cutting operation, said lid cutter when in said lid-cutting position being urged by resistance of a can lid being cut in a direction to rotate said hub and lever and thereby maintain said switch closed so long as any portion of the lid is uncut relative to the can, and spring means operatively associated with said switch for normally biasing said switch open and tending to move said lever against the resistance force of the can top being cut.

References Cited in the tile of this patent UNITED STATES PATENTS 2,893,116 Aberer et al. July 7, 1959 3,018,549 Spielman Jan. 30, 1962 

1. AUTOMATIC CUT-OFF MECHANISM FOR AN ELECTRIC CAN OPENER COMPRISING A BASE, A CAN ROTATING SHAFT JOURNALED THEREIN, A CAN ROTATING WHEEL ON SAID SHAFT, A MOTOR, STEPDOWN GEARING BETWEEN SAID MOTOR AND SAID CAN ROTATING SHAFT, SAID BASE HAVING AN OPENING SPACED FROM SAID CAN ROTATING SHAFT, A LEVER HAVING A HUB ROTATABLE IN SAID OPENING, A RETAINER PLATE FOR SAID LEVER EFFECTIVE TO RETAIN SAID HUB IN SAID OPENING, A CAN LID CUTTER CARRIED BY SAID LEVER AT A POSITION OFFSET FROM THE AXIS OF ROTATION OF SAID HUB, A CONTROL SWITCH FOR SAID MOTOR, SAID CONTROL SWITCH BEING NORMALLY RESILIENTLY URGED INTO OPEN POSITION, SAID LEVER IN CAN OPENING POSITION OPERATING TO CAUSE SAID CONTROL SWITCH TO CLOSE, SAID CUTTER IN THE LID CUTTING POSITION BEING URGED IN A DIRECTION TO ROTATE SAID HUB AND LEVER INTO SWITCH CLOSING POSITION, AND THEREBY KEEP SAID CONTROL SWITCH CLOSED AS LONG AS ANY PART OF THE LID IS UNCUT RELATIVE TO THE CAN BUT ALLOWING IT TO OPEN WHEN THE LID IS COMPLETELY SEVERED TO EFFECT AUTOMATIC CUT-OFF. 